At a news conference in Moore, Fallin said she had activated the National Guard and rescuers were trying to find all those who were missing.
“Our hearts are just broken for the parents that are wondering (about) the state of their children that have been in the schools that have been hit today,” Fallin said.
Five schools were damaged by Monday's storm, she said.
“We have brought in rescue dogs to go through the debris itself. It will be dark pretty soon and we want to do everything we can to continue to look for those who might be lost in this tragedy,” Fallin said.
“We've had a massive tornado, a huge one that has passed through this community. We do know there are fatalities. ... We know there are a lot of injuries.”
Fallin said a reunification center has been set up at St. Andrew's United Methodist Church at SW 119 and S May Avenue in Oklahoma City.
Police said later that some children were being reunited with families at First Baptist Church of Moore, at NE 27 and Interstate 35.
A woman in OU Medical Center's waiting room, who would only identify herself as Dina, said a friend who owns A Step Above day care in the tornado-damaged area had told her she was heading to the hospital with the children. She said the owner had texted her earlier to say “we're alive but buried under.”
“There's damage at a wide scope at this point,” EMSA spokeswoman Lara O'Leary said Monday afternoon.
Among the many damaged businesses were the Moore Branch of Tinker Federal Credit Union and Warren Theatres.
Officials reported the credit union branch at 400 SW 6 sustained “considerable damage” and would be closed indefinitely. Credit union employees hunkered down in the vault to weather the storm and were released unharmed from the vault later with the help of first responders. All personal safe deposit boxes were reported secure.
Jill Gottschalk, an assistant in Warren Theatres' corporate office in Wichita, Kan., said there were no reports of injuries to theater employees or patrons.
“Obviously, we are just in a loss of words right now,” she said. “Our thoughts and prayers are with everyone ... Anything any of us can do here we're definitely in gear to go do it.”
All EMSA emergency crews were dispatched to the damaged area. Edmond police also were being sent to the area.
Gas leaks were reported in Moore, where a destroyed home could be seen burning in one of the damaged neighborhoods Monday afternoon.
Law enforcement officers closed Interstate 35 in both directions between Interstate 240 and Indian Hills Road.
Officers also closed the H.E. Bailey Turnpike at State Highway 4 due to the tornado.
Monday afternoon's tornado was strikingly similar to the gigantic May 3, 1999, tornado that ravaged Moore and south Oklahoma City, killing 44, injuring hundreds and destroying thousands of homes.
Monday's huge wedge-shaped funnel initially dropped from the skies at 2:56 p.m. near Newcastle and began churning northeastward through southwest Oklahoma City and Moore, spewing power flashes and mercilessly grinding up everything in its path.
In Newcastle, 35 to 40 homes were either severely damaged or destroyed and one person was critically injured, said Kevin Self, Newcastle emergency manager.
A section of Interstate 44 was closed for a time due to a ruptured gas line, but the leak was capped and the highway reopened about sundown, Self said.
The tornado crossed Interstate 35 near the Warren Theatres before continuing east-northeastward and eventually lifting west of Lake Stanley Draper at 3:36 p.m., according to the National Weather Service.
The debris path was several blocks wide and stretched for 20 miles. The National Weather Service said preliminary indications are the tornado was at least an EF4, which indicates wind speeds of up to 200 mph.
The Oklahoma Corporation Commission reported more than 61,500 power outages related to the storm.
Another tornado reportedly touched down near Sparks in southern Lincoln County, but no immediate damage estimate was available, according to a Lincoln County Emergency Management spokeswoman.
The tornadoes struck while Oklahomans still were staggering from Sunday night's tornadoes, which destroyed homes in several other communities and left two dead.
Contributing: Staff Writers Nolan Clay, Matt Dinger, Silas Allen, William Crum, Jaclyn Cosgrove, Diana Baldwin, Andrew Knittle, Zeke Campfield, LEIGHANNE MANWARREN, Michael McNutt, Chris Casteel, Ben Luschen, Carrie Coppernoll, Matt Patterson, Brandy McDonnell and Carla Hinton, and The Associated Press.wmctv.com: Watch time-lapse video of the tornado
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